The present disclosure relates to a method of designing a multiple-tuned filter (hereinafter, referred to as an MTF) according to characteristics of a high voltage direct current (hereinafter, referred to as an HVDC) system.
In an HVDC system, a harmonic filter suppresses harmonics, which are generated while power is converted by operating a converter, from being introduced into an alternating current (AC) system and also serves as a reactive power source due to consumption of reactive power. Most current-type HVDC systems operate with 12 pulses and thus generate (12±1)th characteristic harmonics such as 11th, 13th, 23rd, and 25th harmonics. In particular, 11th and 13th harmonics have large amplitudes, and thus 11th and 13th filters are used to reduce the 11th and 13th harmonics.
In a current-type HVDC system, most converters operate with 12 pulses. The ±80 kV 60 MW HVDC system in Jeju island of South Korea also includes a 12-pulse converter that uses serial connection of two 6-pulse groups.
In an HVDC system, a single tuned filter (STF) or a double tuned filter (DTF) is widely used as a harmonic filter. Equations associated with a serial or parallel impedance of the filter may be used to design such a filter.
In the filter design, since passive elements included in the filter may be determined through manual calculation on the basis of their designed ratings and performance, there is no accurate, efficient, and standardized method.
Furthermore, when the filter is designed, there is no solution considering prices. Thus, in view of manufacturers, a design method that may consider production cost as well as performance has not been proposed yet.